So today while going downhill DTC, ABS and EBRAKE light went off (all yellow) and on little window in the cluster the abs 4x4 error lit up yellow as well. Tried to shut cat off an restart error was still there. I plugged in my COBB and no error there and I did a reset on the ecu. Error is gone and I made about 50km to test it out to make sure. Now removed cobb and went to dealership. They say it might have been a bug in the ecu or some contaminant on a sensor and to came back if it lit up again. Now i'm worried to flash it again and that the error pop up as COBB will erase the error.

So today while going downhill DTC, ABS and EBRAKE light went off (all yellow) and on little window
In cluster abs 4x4 error lit up yellow as well. Tried to shut cat off an restart error was still there. I plugged in my COBB and no error there and I did a reset on the ecu. Error is gone and I made about 50km to test it out to make sure. Now removed cobb and went to dealership. They say it might have been a bug in the ecu or some contaminant on a sensor and to came back if it lit up again. Now i'm worried to flash it again and that the error pop up as COBB will erase the error.

If you're still in warranty (idk if it transfers) you should really bring it in to have it looked at/fixed.

My 4x4 light only came on so I did a lot of research and it could be something with the transfer case which could cost anywhere from $1000-3000 to fix. It should be safe to drive with any yellow errors but if they turn red then it's a problem (from what I've read).

The description of a replacement part for X5 that I saw said that the warranty is only guaranteed if all 4 tires are replaced at the same time (maybe time of install?), so tires may have something to do with it, all though wider rims shouldn't effect it at all. Only if the tires don't have the same diameter then it might cause a problem, which I have one tire different (from replacing a flat apparently... its a used car) so I think that may have caused mine, but my error light went away so I stopped looking into it...

I do have a CPO warranty on my car so then I should not be worried ? For now the message has not come back (100+ km done since removed cobb) and the car drives fine even tho the lack of power (due to back to stock).

What were the road conditions like when the warning appeared, how were you driving, and have you replicated them since clearing the codes & uninstalling the Cobb?

What I am getting at is if it was icy or whatever and maybe you were getting on it a little, you exposed an incipient problem with the AWD system. I would try to get the problem to come back w/o Cobb installed and then document it and take it back to the dealer.

How I was driving : deceleration and was going less than 30kph and braking for the upcoming stop at the botton of the small downhill.

That's why I found it weird to happen at that time. Only other time I saw this error was after disconnecting the battery (and I did check the battery connection to make sure). Did try to replicate the issue in similar condition and 150km later still didnt came back. Will keep cobb removed for a week at least to see what happens.

How I was driving : deceleration and was going less than 30kph and braking for the upcoming stop at the botton of the small downhill.

That's why I found it weird to happen at that time. Only other time I saw this error was after disconnecting the battery (and I did check the battery connection to make sure). Did try to replicate the issue in similar condition and 150km later still didnt came back. Will keep cobb removed for a week at least to see what happens.

If it were my car after waiting a week or so if it did not reoccur I'd install the Cobb back in and not worry about it. Carry the Cobb in-car just in case it happened again and for some reason the car needed a tow to the dealership.

Error came back today but after 2 power cycle didnt stayed on (before I could go to dealer). Now the car is sitting at the dealer to do a diagnostic but if error is not present it doesnt stay in any memory. Will see what they say about it.

Get ready to replace your transfer case motor. Those are the exact symptoms I had both times I replaced it. If you're under warranty have them do it, otherwise I would recommend sourcing a second hand part and giving the job a shot yourself (or having an indy do it). It's literally a two minute job once you're under the car, and stealership will likely charge you $800+ for the job given that just the part at the dealer is over $600. I was able to find a full tcase with the motor for $200 out of a wrecked 328xi and the second motor I got from a recycler for $125+S&H. The extra unreliability that comes with the xdrive cars is real (and expensive if handled at the stealer), but the parts are easily found second hand given that all AWD e9x/e6x use the same drivetrain parts.

Get ready to replace your transfer case motor. Those are the exact symptoms I had both times I replaced it. If you're under warranty have them do it, otherwise I would recommend sourcing a second hand part and giving the job a shot yourself (or having an indy do it). It's literally a two minute job once you're under the car, and stealership will likely charge you $800+ for the job given that just the part at the dealer is over $600. I was able to find a full tcase with the motor for $200 out of a wrecked 328xi and the second motor I got from a recycler for $125+S&H. The extra unreliability that comes with the xdrive cars is real (and expensive if handled at the stealer), but the parts are easily found second hand given that all AWD e9x/e6x use the same drivetrain parts.

Fortunately i'm still under the 80 000km warranty and the car is CPO till march 2015 if not mistaken so I'm really not nervous about cost for now just hoping that the error come back so that they can change the motor or the t-case